[dpw]

I'm 38.

If you run Linux on an x86 desktop, you use code that I wrote in 1997: The MTRR support in http://cgit.freedesktop.org/xorg/xserver/tree/hw/xfree86/os-... (big chunks of that are unchanged in 16 years; I also collaborated on the kernel-side MTRR support, but that has been rewritten a couple of times by now).

It's probably possible to find online traces of code I wrote a couple of years before that. But I think that is the oldest code still in use.